Diffusion transfer processes and products comprising formation of a cyanine dye at receiving element



NOV. 3, 1970 5, BLQQM 3,537,851

DIFFUSION TR FER PROCESSES AND PRODUCTS COMPRISING FORMATION A CYANI DYE A ECEIVING ELEMENT Filed y 1, 8

n v I/SUPPOYRT Q/LAYER CONTAINING DEVELOPING AGENT I4-////' PHOTOSENSITIVE LAYER |6 :21, RUPTURABLE CONTAINER A IMAGE RECEIVING LAYER CONTAINING CYCLOAMONIUM ouATERNA'R SALT A pH REDUCTION LAYER N SUPPORT I5 FIG. I

f 2% vz|- VSUPPMT L/PHOTOSENSITIVE LAYER AL/RUPTURABLE CONTAINER LAYER CONTAINING DEVELOPING AGENT IMAGE RECEIVING LAYER N'I'AINING CYCLOAMONIUM QUATERNA SALT PH REDUCTION LAYER V 27 SUPPORT 25 FIG. 2

3|- SUPPORT I A LAYER CONTAINING DEVELOPING AGENT :2 AND pnoTosENslTlvEslLvER HALIDE I RUPTABLE CONTAINER flnem zswwsumsmswzz'w" as v l-l REDUCTION LAYER, SUPPORT 35 FIG. 3

/SUPPORT PHOTOSENSITIVE LAYER RU PTURABLE CONTAIN ER IMAGE RECEIVING LAYER CONTAINING CYCLOAMONIUM QUATERNARY SALT -pH REDUCTION LAYER INVENTOR.

ATTORNEYS United States Patent 3,537,851 DIFFUSION TRANSFER PROCESSES AND PROD- UCTS COMPRISING FORMATION OF A CYA- NINE DYE AT RECEIVING ELEMENT Stanley M. Bloom, Waban, Mass., assignor to Polaroid Corporation, Cambridge, Mass., a corporation of Dela- Ware Filed July 1, 1968, Ser. No. 741,549 Int. Cl. G03c 5/54, N58

US. Cl. 96-29 14 Claims ABSTRACT OF THE DISCLOSURE This invention relates to photograph and more particularly to products, compositions and processes for obtaining color images.

Many systems are known for preparing color images by diffusion transfer. In such prior systems, for example, a photosensitive element containing at least one light-sensitive silver halide emulsion and associated layer of color-providing material, e.g., a complete dye or a color coupler, is exposed and then developed to provide, as a function of development, an imagewise distribution of color-providing material which is transferred, by imbibition, to a superposed image-receiving element, e.g., a dyeable sheet material, to provide thereon a monochromatic or multi-color image of the original subject matter. Many of these prior systems rely for color transfer image formation upon mechanisms for providing, as a function of development, a differential in mobility or diffusibility in the processing fluid of the color-providing material.

Typical of such systems is the one described in US. Pat. No. 2,983,606, issued to Howard G. Rogers, which utilizes a compound called a dye developer which in its oxidized state is less mobile than in its unoxidized state. Typical coupling mechanism processes for providing a colored image are set forth in US. Pat. Nos. 2,661,293 and 2,698,798, both issued to Edwin H. Land.

The novel image-forming system of the present invention utilizes an oxidative coupling reaction between difunctional compounds to provide a colored, higher molecular weight, substantially nondifusible reaction product as a function of development. This oxidative coupling process is effected between an enamine moiety and a quinone or quinonimine radical of a silver halide developing moiety. The difunctional compound preferably comprises one of each of these moieties in a single molecule. Enamiue moieties are provided in the image receiving element, preferably by imbibition, which interact with a cycloammonium quaternary compound found in the image-receiving element, whereby a cyanine dye is formed in the areas of the image-receiving element corresponding to the unexposed and undeveloped areas of the photosensitive element.

ice

Accordingly, a primary object of this invention is to provide novel processes, products and compositions for preparing color images.

Another object is to provide novel products and processes useful for obtaining color images by diffusion transfer.

Still another object is to provide novel systems for obtaining as a function of development of an exposed photosensitive element, a differential in the ditfusibility or mobility of a color providing material, whereby an imagewise distribution of the mobile color providing material is transferred, by imbibition, to an image-receiving element to provide a color transfer image upon reaction with a compound found therein.

Yet another object is to provide novel systems for obtaining both a positive and a negative color transfer image both of which are capable of providing good pictorial information, by the utilization of novel compounds, which upon development, undergo a chemical interaction to provide a color-forming material in the photosensitive element, and which subsequent to diffusion to the image-receiving element, undergo a coupling-displacement reaction with a compound found in saidimagereceiving element whereby a moiety present in said compound is displaced such as to provide a color image on the image-receiving element.

Other objects of the present invention will in part be obvious and will in part appear hereinafter.

The invention accordingly comprises the several steps and the relation and order of one or more of such steps with respect to each of the others, and the product possessing the features, properties and the relation of elements which are exemplified in the following detailed disclosure, and the scope of the application of which will be indicated in the claims.

For a fuller understanding of the nature and objects of the invention, reference should be had to the following detailed description taken in connection with the accompanying drawings wherein:

FIG. 1 is a diagrammatic cross-section of one embodiment of a film unit forming the subject of this invention and illustrates a product comprising a photosensitive element, a rupturable container and a print-receiving element;

FIG. 2 is a diagrammatic cross-section of another embodiment of a film unit wherein the order of the layer containing the developing agent and the photosensitive layer are reversed in the photosensitive element;

FIG. 3 is a diagrammatic cross-section of still another embodiment of a film unit forming subject matter of this invention; and

FIG. 4 is a diagrammatic cross-section of a further embodiment of a film unit forming subject matter of this invention.

In general, the photographic processes and products disclosed herein are concerned with the development of an exposed photosensitive silver halide layer to provide a colored negative image in the photosensitive layer and a colored positive image in or on another layer which comprises a print-receiving layer. The developing agent which is oxidized as a result of silver development undergoes an oxidative coupling and forms a dye image which is coextensive with the silver image. The unreacted developing agent in the undeveloped areas is transferred, by diffusion, to the print-receiving layer and forms thereupon an imagewise distribution of unreacted developing agent which without oxidation undergoes a coupling displacement reaction with a cycloammonium quaternary salt in the image-receiving layer to effect formation of the desired dye positive. Oxidation of any excess transferred unreacted developing agent, not reacted with said salt, must be prevented to avoid the oxidative coupling reaction, prior to separation of the photosensitive element from the image-receiving element. After separation of the elements, aerial oxidation of excess developing agent cannot be prevented. However, by incorporating a pH reducing agent into the positive element and/or the photosensitive element which takes effect after the desired positive image formation mechanism has transpired, it is seen that the oxidative coupling reaction is prevented from occurring.

The term enamine was coined by Wittig and Blumenthal in 1927 and is used to refer to compounds which are il-unsaturated amines. The term cyclic enamine is used to describe a compound in which both the nitrogen and double bond are contained in a mono or bicyclic ring system. The structural moiety represented by enamine is similar to that of an enol wherein the hydroxyl group is replaced by a nitrogen atom.

enol

Typical examples of cyclic enamine precursors are quaternary pyridine and quinoline derivatives substituted with a methyl group in the alpha or gamma position. When such compounds are placed in an alkaline environment, the enamine form of the compound is generated.

1 L W l III CH3 N CH2 CH2 6 CH5 enamine Since the term vinylog is used to describe compounds which differ by one or more vinylidene linkages, the vmylog of an enamine has the structure the same as a dienamine.

In this application, the term enamine is intended to include not only enamines but also dienamines, and the eamines will be generated from the disposition preferably of cyclic as opposed to acyclic quaternary ammonium compounds in a basic medium such that the enamine structure is generated in situ. Further information on enamines will be found in an article by J. Szmuszkovicz in Advances in Organic Chemistry, Methods and Results, volume 4, 1963, published by Interscience, New York, NY. Further information on the principle of vlnylogy will be found in Advanced Organic Chemistry by Reynold C. Fuson, copyright 1950, published by I ohn Wiley and Sons, New York, NY.

It must be appreciated, however, that the mere placement of an alpha or gamma substituted methyl quaternary ammonium compound in a given amount of alkali will not automatically generate the enamine derivative. The generation is dependent upon the acid strength of the compound. By this is meant the ability of a fixed amount of alkali to remove a proton therefrom. Thus, if one mole of methyl pyridine and one mole of an alpha picoline, i.e., methyl quinoline, were placed in the same amount of NaOH, since the enamine generation is an equilibrium reaction, it would be found that the methyl pyridine would display the properties of methyl pyridine, while an alpha picoline would display the properties of its enamine derivative due to the inherent difference in acid strengths. Methyl pyridine will likewise generate its enamine, but only upon an increase in the concentration of alkali.

The term nondiffusible as used herein has the meaning commonly applied to the term in color photography and denotes materials which, for all practical purposes, do not migrate or wander through organic colloid layers such as gelatin, in the presence of an aqueous alkaline processing solution, within a predetermined processing period. The same meaning is to be attached to the term immobile. The term diffusible as applied herein has the converse meaning and denotes materials which have the property of diffusing effectively through colloid layers in the presence of an aqueous alkaline processing solution. Mobile has the same meaning.

The term oxidative coupling is used to describe the reaction wherein an oxidized molecule interacts with another molecule (unoxidized) of the same species or with a molecule of another species. In more detail, the procedure entails the oxidation of an organic compound, such as phenol, whereby a free radical generated therefrom may attack another molecule of the same species to form a dirneric structure containing a free radical which, if not capped by an atom of hydrogen after forming the dimer, is capable of continuing the propagation of the chain to form a relatively high molecular weight homopolymeric product. In other instances, the free radical can be generated not from the moiety which is oxidized but from another moiety.

In the processes of this invention, a quaternary ammonium radical forms its enamine derivative which as is known, contains a free radical in the alkaline processing solution. When the silver halide developing agent, usually a hydroquinone, i.e., a substituted phenol, is oxidize, the free radical attacks the ring to form a new carbon to carbon bond. Since more than one enamine radical is present, the reaction is capable of continual propagation to form a relatively high molecular weight product. It is seen that since the hydroquinone radical is only oxidized in the areas of development, the formation of the high molecular weight nonditfusible product occurs as a function of development. By careful selection of the entire moiety that contains the enamine radical, it is possible to form a chromophore upon the interaction with the developing radical and provide a colored image.

In the preferred mode of this invention, both the quaternary ammonium radical and the silver halide developing radical comprise parts of one molecule. These two radicals are joined by a linking group.

While it is not intended to be restrictive to any particular theory, it is believed that the reaction mechanism upon which image formation is predicated in the photosensitive element, i.e., negative image, and the imagereceiving layer, i.e., positive image, may be illustrated by the following reactions between the enamine moiety and the oxidized silver halide developing radical herein illustrated as a quinonyl radical derived from a hydroquinone, for the attainment of the negative image and the coupling displacement reaction between the enamine and a cycloammonium quaternary compound found in the image-receiving element which is capable of coupling with said enamine, for the positive image.

1 Omar-0:1

Since the enamine radical is double ended, i.e., attached to another enamine radical, or preferably attached to a developing radical, it is seen that a colored immobile polymer is built up as a function of development in the photosensitive layer The preferred compounds utilized in the present invention thus are defined as being within the structure:

DEV-LINK-EN wherein DEV in an unsubstituted, alkylsubstifllted or halogen substituted monovalent radical selected from the group consisting of phenyl and naphthyl rings, substituted in ortho or para positions with respect to each other by -OH and NH at least one of said positions being substituted by OH; or the precursors thereof, wherein the precursor group for OH is an alkoxy or alkoxymethoxy group, and the precursor for -NH is NO LINK is a divalent linking radical of the formula:

Ag-CHg OC2H4] m" TIGHT or of the formula:

wherein A is selected from the group consisting of oxygen or sulfur, e is 1 or 0, m is a number of from 0 to 4 inclusive, n is a number of from 0 to 8 inclusive, the sum of m+n being not greater than 8; and

EN is a cyclic or acyclic quaternary ammonium radical which is capable of generating an enamine and which radical is bonded through the pentavalent nitrogen atom thereof to LINK.

' As examples of useful dihydroxyphenyl radicals comprising DEV substituents, mention may be made of ortho dihydroxyphenyl, para-dihydroxyphenyl and nuclear-substituted derivatives thereof, e.g., chloro, methyl, phenyl, and/or methoxy-substituted derivatives thereof, particularly nuclear-substituted p-dihydroxyphenyl such as methylhydroquinonyl, pmethylphenylhydroquinonyl, chlorohydroquinonyl, methoxyhydroquinonyl, 2,6-dimethylhydroquinonyl, 2,6-dimethoxyhydroquinonyl, 2-methoxy-6- methylhydroquinonyl, 2,3-dimethylhydroquinonyl, 2,5,6- trimethylhydroquinonyl, etc.

As examples of useful dihydroxynaphthyl silver halide developing radicals comprising DEV mention may be made of any of the above dihydroxyphenyl radicals wherein the benzene ring is replaced by a naphthalene ring and the other substituents are appropriately situated.

As examples of useful dialkoxyaryl and dialkoxymethoxyaryl radicals for this invention. mention may be made of the above dihydroxyphenyl radicals wherein the hydroxyl groups are replaced by alkoxy and methoxyalkoxy groups containing from 1 to 5 carbon atoms in the alkoxy portions, and the aryl ring is either a benzene ring or a naphthalene ring.

As examples of useful nitrogen containing silver halide developing radicals, mention can be made of any of the above-mentioned dihydroxyaryl radicals wherein one of the hydroxyl groups is replaced by an --NH group. The precursors for such nitrogen containing developing radicals are those radicals which contain an NO group ortho or para to the hydroxyl precursor group. As examples of such nitroalkoxyaryl and nitroalkoxymethoxyaryl radicals, mention may be made of 2 nitro, 5 ethoxy benzene and any of the dihydroxyaryl radicals above wherein one hydroxyl group is replaced by a nitro group and the other hydroxyl group is replaced by an alkoxy or alkoxymethoxy group.

LINK, the divalent linking radical of the formula indicated above, comprises a unit, A --CH wherein A has been previously defined, joined to a linear divalent hydrocarbon group, or a linear divalent hydrocarbon.

group interrupted by atom(s) of sulfur or oxygen such that ether or thioether linkages are formed. The proviso exists that there must be at least two carbon atoms interspaced between the last oxygen or sulfur atom and the moiety --EN.

As illustrations of suitable alkylene radicals comprehended as the linear divalent hydrocarbon portion of LINK, mention may be made of radicals such as As examples of some hydrocarbon substituents containing unsaturation that are suitable for such portion of LINK, mention can be made of radicals such as As examples of linear divalent hydrocarbon groups that are interrupted by atom(s) of oxygen or sulfur, mention may be made of As has been indicated, EN is a quaternary ammonium radical which is capable of generating an enamine. While the EN moiety can be either cyclic or acyclic, the more preferred moieties are cyclic.

Quaternary ammonium compounds are organic compounds which contain a pentavalent nitrogen atom. Generally, they can be considered as derivatives of ammonium compounds wherein the four valences usually occupied by the hydrogen atoms are occupied by organic radicals. Generally, the organic radicals are joined directly to the pentavalent nitrogen through a single or double carbonto-nitrogen bond. The term, quaternary ammonium, as used in this application, is intended to include compounds wherein the pentavalent nitrogen is one of the nuclear atoms in a heterocyclic ring, and such heterocyclic quaternary ammonium compounds are preferred. It will be seen that the other atoms comprising the heterocyclic ring can be either all carbon atoms, as well as carbon atoms interspaced with atoms of sulfur, selenium, oxygen and nitrogen. It will be further seen that the term heterocyclic ring is intended to encompass not only single ring structures but also fused rings, such as quinoline. It is seen that EN, to be able to generate an enamine, must contain, when cyclic, a carbon atom alpha to the nitrogen atom within the ring which has bonded thereto an alkyl group not in the ring which contains at least one hydrogen atom, or EN can be a vinylog thereof. A similar relationship exists for acyclic EN moieties.

As examples of compounds wtihin the formula:

DEVLINKEN wherein DEV and LINK are as previously defined, mention may be made of those represented by the following formulae:

and

wherein Q is an acyclic hydrocarbon or halogen substituted hydrocarbon group, M represents the atoms necessary to complete a heterocyclic ring, X is an anion, e.g., methylsulfonate, bromide, chloride, toluene sulfonate, etc., and T is an alkyl radical.

Typical quaternary ammonium radicals which are capable of generating an enamine and which contain only carbon atoms and the tertiary nitrogen atom within the heterocyclic ring include alpha picolinium, gamma picolinium, alpha quinolinium, gamma quinolinium and 1- methyl isoindolenine.

Quaternary ammonium radicals which are capable of generating an enamine and which contain in addition to carbon atoms and a tertiary nitrogen atom within a heterocyclic ring, other atoms such as an atom of selenium, oxygen, sulfur or an additional nitrogen atom can be employed in the present invention as EN. Such radicals include those derived from the thiazole, selenazole, oxazole, imidazole and indole ring systems among others.

The anion represented by the designation X in the formulae comprises those anionic acid radicals customary in the cyanine dye art, for example, chloride, bromide, iodide, methylsulfate, ethylsulfate, p-toluenesulfonate, benzenesulfonate, acetate, propionate, cyanate, perchlorate, and the like.

While the acyclic alkyl group bonded to the alpha carbon can contain any number of carbon atoms provided that the unreacted enamine is capable of diffusing, it is preferred to use a methyl, ethyl or propyl group.

It should be apparent from above that any LINK substituent that comprises purely hydrocarbon units contains at least two carbon atoms in the chain. This is necessary to avoid cleavage of the molecule when it is placed in a strong alkaline environment. If oxygen or sulfur atoms are present in the chain, there should not be an atom of one of these bonded to the same carbon atom as is bonded to the pentavalent nitrogen atom of EN; nor should such an atom be bonded directly to EN. Here, too, the necessity for two carbon atoms between such oxygen or sulfur is to avoid cleavage in an alkaline medium.

As examples of compounds within the scope of the formula:

DEVLINK--EN suitable for use in this invention, mention may be made of the following:

Compounds of the structure:

DEVLINK-EN can be prepared among other ways by the alkylation of an amine. This method of preparation forms part of the subject matter of my copending application Ser. No. 741,293, filed concurrently herewith.

While that application relates to the preparation of compounds of the formula:

DEVLINKQUAT it is seen that the compounds of the instant invention comprise a subgenus thereunder. The method disclosed therein comprises reacting a tertiary amine which has on the ring carbon atom alpha the nitrogen atom, a carbon atom which for cyclic compounds is located outside the ring and which has at least one hydrogen atom bonded thereto, such as 2-methyl pyridine, i.e., alpha picoline, or a vinylog of such a compound, with a halogen substituted alkyl acetal, such as one of the formula:

CHzBr HsC O O CH:

wherein y is an integer of from 1 to 5 inclusive. This intermediate product is reacted with hydrogen ion, such that the aldehyde derivative is prepared. This aldehyde compound is reacted in base with an acetophenone such as the compound of the formula:

OCH:

to give rise to a product of the formula:

0 CH: E

l OOH:

11 which can then be reduced, such as by hydrogen, to a dialkoxyphenyl quaternary ammonium compound:

(|)CH3 E OCHa Subsequent treatment of the alkoxy groups with a dealkylating agent gives rise to the hydroxyl derivative of the alkoxy compound. Details on this step will be set forth further on in the specification.

The preferred mode of preparing the enamine generating compounds used in the present invention, and which do not contain the optional A group, i.e., the atom of oxygen or sulfur, and which have an all hydrocarbon LINK, is by the alkylation of a tertiary amine which is substituted in the manner previously indicated, in the absence of heat, so as to avoid side reactions. This reaction can be illustrated as follows. A compound of the formula:

H[CH2]yL wherein y is as previously defined, z is an integer of from 2-10 inclusive and X is halogen,

or CH SO etc., or its ortho dialkoxy equivalent, is reacted with a tertiary amine, as for instance a compound of the formula:

and a product of the formula:

is obtained. Dealkylation of the alkoxy groups prepares the dihydroxy compound.

Compounds containing the optional A group, namely an atom of oxygen or sulfur and an all hydrocarbon remainder of LINK, are prepared by a slightly different alkylation process. This is necessary in view of the fact that the dihydroxy compounds cannot be prepared by the aforementioned synthesis in view of the inability of any reagent to differentiate between the alkoxy groups in the 2,5 positions and the alkoxy group that would be in the 1 position. Therefore, to prepare compounds containing the optional A group, an alkoxyalkoxy compound such as the one of the formula:

or its ortho equivalent, wherein A, y and z are as previously defined, is reacted with a compound such as toluene sulfonyl chloride in an organic base such as pyridine to prepare an intermediate of the formula:

OCHZCHCHZLJI which is then reacted with any tertiary amine, properly substituted, e.g., Z-methyl quinoline, to yield an end product of the formula:

Treatment of the above with dilute mineral acid removes the alkoxymethyl groups and gives the dihydroxy product.

Compounds which contain ether or thioether groups in the remainder portion of LINK, i.e., that portion of LINK which follows the moiety A CH are prepared by treating compounds of the following formulae:

y and A are as defined previously, or their ortho equivalents with a reagent such as sodium hydride in dimethylsulfoxide followed by the addition of one mole of ethylene oxide or its sulfur counterpart. More than one ether or thioether units can be added to increase the size of R, by increasing the number of moles of ethylene oxide or ethylene sulfide added in the addition step. The preferred mode, however, is the unimolar addition followed by a sodium hydride treatment between the additions of each mole of ethylene oxide or sulfide. Following the addition of the ether units to the starting materials, the same alkylation processes are carried out, as well as same treatment to remove the alkoxymethyl groups.

While the above synthesis has employed ethylene oxide, it is of course understood that other epoxide units such as propylene oxide etc., can be added in like manner.

The removal of the protective alkoxy groups to form the desired hydroxy substituted compounds may be accomplished by known hydrolysis techniques. A typical demethylation process involves complexing the group to be removed with boron tribromide, followed by decomposition of the resulting complex with water. Another demethylation process comprises treatment of the methoxy intermediate with aqueous HBr or HBr in acetic acid.

The various reaction conditions, e.g., time, temperature, pressure, selection of solvents, etc., for the DEVLINKEN compounds are not critical to the practice of this invention unless so indicated and will therefore be readily selected by the skilled artisan in the light of the foregoing descriptive material. The essence of the invention is, therefore, the aforementioned selection of steps, in the order described to obtain the desired end product, as well as the end product itself.

The reaction mechanism upon which positive image formation is predicated may be illustrated by the reaction set forth below. Here too, it is intended that the mechanism be considered as purporting to illustrate what transpires in the image-receiving layer, and as such the applicant should not be limited or restricted to any particular theory concerning said image formation.

Formation of a colored image is caused by the creation of a chromophore which arises as the result of a couplingdisplacement reaction on the image-receiving layer in the areas corresponding to the undeveloped areas of the photosensitive layer.

Enamine functions are provided in the image-receiving layer, by diffusion from the photosensitive layer which couple with a cycloammonium quaternary compound, by displacing a moiety of said compound.

As was indicated previously, the enamine is written as:

I lC=CHz The cycloammonium quaternary compound is written as:

wherein Z represents the atoms necessary to complete a heterocyclic ring, R is a ballast group and R is an alkyl group, all three of which groups will be defined in more particularity infra.

The coupling displacement reaction to create a cyanine dye in the image-receiving layer can be illustrated as and are isomeric forms of a cyanine dye. :It is seen that cycloammonium quaternary compounds which can undergo the coupling-displacement reaction to form a colored product of the nature of a cyanine dye include those of the formula:

wherein R is an alkyl group of 1-12 carbon atoms inclusive, including haloalkyl groups of 1-12 carbon atoms inclusive; R is a ballast group used to provide an in crease in the molecular Weight of the compound and thereby limit and control its diffusion and as such comprises an aliphatic or aromatic group, or a group comprising a mixture thereof, and which group contains from about 6 to about 18 carbon atoms; Z comprises the atoms necessary to complete a heterocyclic ring.

As examples of R groups, mention may be made of methyl, chloromethyl, ethyl, isopropyl, heptyl, nonyl, dodecyl, etc.

As examples of R groups, mention may be made of hexyl, octyl, nonyl, dodecyl, pentadecyl, octadecyl, etc.

As examples of heterocyclic nitrogen containing rings, mention may be made of pyridine, quinoline, and indolenine, as well as the rings of the selenazole, oxazole, thiazole, imidazole, etc., series which have been set forth previously in connection with the discussion pertaining to the enamine generating compounds.

The anion needed to balance the charge of the nitrogen atom can be any of those designated previously for X, the balancing anion of the enamine generating compound. This anion can exist separately or be a part of the cycloammonium compound.

As examples of cycloammonium quaternary compounds which are suitable for this invention, mention may be made of the following:

CzHr

The cycloammonium quaternary salts may be prepared by the reaction of a compound:

or other halide, with a mercapto compound:

RSH

to prepare an intermediate:

which is then quaternized as, for instance, by reaction with a compound of the formula:

ozntoas-ona to prepare an end product of the formula:

N+ (IJQHE wherein R and Z are as previously described.

A further understanding of the invention will be gained from a consideration of photographic products useful for carrying it into effect. In this regard, there is schematically shown in FIG. 1 a film unit making use of a photosensitive element comprising a support 11 of paper or film base material upon which there is mounted, in the order named, a layer 12 comprising a developing agent of the character with which this invention is concerned, and a photosensitive layer 14 of silver halide. Layer 12. is penetrable by the liquid processing composition employed so that the developing agent contained therein may be placed in solution. The film unit of FIG. 1 also employs a print-receiving element 15 comprising an image-receiving layer which is liquid permeable and dyeable from alkaline solutions and which has been illustrated as comprising a three layered element wherein the bottom layer 17 is a support material such as paper, a middle layer 18 which is a pH reducing layer and a top image-receiving layer 19 which is dyeable and which contains the cycloammonium quaternary salt.

As shown in FIG. 1, the photosensitive element 10 and the print-receiving element 15, for the purpose of positive image formation, are adapted to be placed in superposed relation with the photosensitive layer or stratum 14 next to the print-receiving layer of element 15.

Also, in the film unit of FIG. 1, a rupturable container 16 adapted to carry an alkaline solution or liquid composition, is shown as positioned transversely of and adhered to the print-receiving element 15. If desired, the container 16 may be adhered to the photosensitive layer. Container 16 is of a length approximating the width of the film unit and is constructed to carry sufiicient liquid to effect negative image formation in an exposed image area of the photosensitive layer 14 and positive image formation in the corresponding image area of the print-receiving element 15. In use, the container 16 is adapted to be positioned between the print-receiving element and the photosensitive element so that it will lie adjacent the edges of the corresponding image areas of these elements which are to be processed by the liquid contents of the container.

In addition to the alkaline material, the processing composition may include viscosity-increasing film-forming reagents such as hydroxyethyl cellulose, sodium carboxymethyl cellulose, etc., and additional reagents performing specific desired functions, e.g., antifoggants, etc., it being understood that any of these ingredients may be present initially in the film unit, in which case the processing composition is formed by contacting the film unit with the aqueous alkaline material. In any event, the processing composition may, if desired, be confined in a frangible container or pod such as described, for example, in US. Pats. Nos. 2,543,181 and 2,634,886, both issued to Edwin H. Land.

While a liquid container 16, which has been illustrated with the film units of this invention, provides a convenient means for spreading a liquid composition between layers of a film unit whereby to permit the processing to be carried out within a camera apparatus, the practices of this invention may be otherwise effected. For example, a photosensitive layer, after exposure in suitable apparatus and while preventing further exposure thereof to actinic light, may be removed from such apparatus and permeated with the liquid processing composition as by coating the composition on the photosensitive layer or otherwise wetting the layer with the composition, following which the permeated layer, still without exposure to actinic light, is brought into contact with a print-receiving element for image formation in the manner heretofore described.

It is also to be kept in mind that the invention may be successfully practiced without the use of a film-forming material in the liquid processing reagent. As an illustration, with this latter expedient, a nonviscous processing composition is particularly applicable and may be applied to the negative material by imbibition or coating practices and may be similarly applied to the print-receiving element before the latter and the negative material are brought into superposed relation or contact for carrying out the transfer of positive image-forming components.

The photosensitive silver halide layers used herein are provided by any of the conventional silver halide emulsions, e.g., silver chloride, silver bromide, silver bromoiodide, silver chlorobromide or silver chlorobromoiodide. The emulsion layer may also contain the various additives heretofore employed in such layers, e.g., optical sensitizers, antifoggants, hardeners, plasticizers, coating aids, speed-increasing materials, ultraviolet absorbers, etc. As examples of typical materials which may be employed for the support mention may be made of films of cellulose nitrate, cellulose acetate, polyvinyl acetal, polystyrene, polyethylene terephathalate, polyethylene, polypropylene, etc., paper, glass and others.

The particular sensitivity range of the photosensitive layer will be chosen to meet particular requirements of the ultimate usage of the product. The silver halide emulsions comprise the photosensitive material and other additives, if any, preferably in a matrix or binder. It is preferred to utilize gelatin as the hydrophilic colloid or binder material although such material as polyvinyl alcohol and its water-soluble derivatives and copolymers, water-soluble polymers such as polyacrylamide, imidized polyacrylamide, etc., and other water-soluble film-forming materials that form water-permeable coats such as colloidal albumin, water-soluble cellulose derivatives, etc., can be utilized in preparing the present photographic elements. Compatible mixtures of two or more of such colloids can also be utilized.

The image-receiving material of the elements 15, 25, 35 and 45 as shown comprise a support which carries a pH reducing layer. Overcoated on said layer is a layer or stratum of a permeable image-receiving material containing the cycloammonium quaternary salt used to obtain the colored image. Typical salts suitable for inclusion in this layer have been described in more particularity above.

As examples of support materials, mention may be made of metal, paper, glass, and film base material, such as polyester terephthalate and other organic polymers.

Methods utilizable to lower pH are known in the photographic art. Several of these are discussed in US. Pats. Nos. 3,362,819 and 3,3 62,821, both issued to Edwin H. Land, Jan. 9, 1968. The preferred mode of achieving such an effect is the use of a layer containing a polymeric acid, as set forth in detail in the just mentioned Land patents.

It should also be noted that a time modulating layer may be interposed between the dye permeable layer and the pH reducing layer, in order to slow down alkali permeation thereto. This layer can comprise such materials as gelatin or polyvinyl alcohol. A subcoat layer comprising a water-impermeable material such as a cellulose ester, i.e. cellulose nitrate, can be interposed between the pH reduction layer and the support.

Image-receiving materials of a dyeable nature, include gelatin regenerated cellulose; polyvinyl alcohol; partially hydrolyzed polyvinyl acetate; nylons; sodium alginate; cellulose ethers, such as methyl cellulose or other cellulose derivatives such as sodium carboxymethyl cellulose or hydroxyethyl cellulose; papers; proteins, such as glue; carbohydrates, such as gums and starch; and mixtures of such materials where they are compatible. Polyvinyl alcohol may be named as a preferred image-receiving material.

Particularly useful image-receiving layers comprise mixtures of polyvinyl alcohol or gelatin and po1y-4-vinylpyridine (such receiving layers are disclosed and claimed in US. Pat. No. 3,148,061, issued Sept. 8, 1964 to Howard C. Haas).

It will be noted that other materials useful in the diffusion transfer prooesses may be incorporated into the image-receiving layer or one of the other layers of the image-receiving element. As an example of such a material, mention may be made of development restrainers such as l-phenyl-5-mercaptotetrazole.

It will be apparent that, by appropriate selection of the image-receiving layer and support from among suitable known opaque and transparent materials, it is possible to obtain neither a colored positive reflection print or a colored positive transparency.

The film unit of FIG. 2 comprises the same elements as are found in the film unit of FIG. 1, namely, the photosensitive element, a rupturable container and an imagereceiving element. The photosensitive element 20 is formed in a manner similar to the photosensitive element and utilizes substantially similar materials for the purposes of construction. In the photosensitive element of FIG. 2, the photosensitive layer is coated directly upon the support and following the drying of this layer, the layer 12 which contains developing agent is coated upon layer 14. Layer 22, as well as layer 12, of FIG. 1, comprise a carrier such as cellulose acetate hydrogen phthalate, in which the developing agent is incorporated. Likewise, the photosensitive element is adapted to be used with a print-receiving element of the nature disclosed in FIG. 1 and in a similar manner for providing, in the print-receiving element, a dye image which is the reverse image of a latent silver halide image formed in the photosensitive element 20 upon exposure thereof.

The photosensitive element of FIG. 3 is formed in a similar manner to the elements of FIGS. 1 and 2, and it uses substantially similar materials for the purpose of construction. It, too, is adapted to use with an image or print-receiving element. In this embodiment of the invention, the developing agent and the photosensitive silver halide grains are incorporated into the same layer, 33.

A suitable carrier material for layer 33 is one which, when subjected to hydroxyl ion or alkaline liquids, will swell sufiiciently to release the developing agent contained therein. Examples of carriers include gelatin, zein, polymethacrylic acid, shellac and cellulose acetate hydrogen phthalate.

FIGS. 1, 2 and 3 illustrate constructions wherein the developing agent is located in a stratum in front or in a stratum in back of the photosensitive layer, i.e., in back being between the photosensitive stratum and the support of the photosensitive element. FIG. 4 illustrates an embodiment wherein the developing agent is located in the processing composition found in the rupturable container 46. Photosensitive element 40 comprises a support 41 upon which is found a layer 44 containing photosensitive silver halide.

The film units depicted in FIGS. 1, 2, 3 and 4 are all adapted for providing in their image-receiving elements, a colored image which is the reverse image of a latent silver halide image formed in their respective photosensitive elements upon exposure thereof.

It is to be noted that for the sake of brevity, that in the specification, the component parts of the image-receiving element have only been described in the discussion of FIG. 1. It is to be understood, however, that the embodiments of FIGS. 2, 3 and 4 utilize image-receiving elements of the same construction.

When any of the photosensitive elements such as those illustrated in FIGS. 14 are exposed and then processed by spreading an aqueous alkaline processing composition between the thus exposed element and an image-receiving layer or dyeable stratum shown as integrated into the image-receiving elements 15, 25, 35 and 45, a positive colored transfer image is obtained, in addition to the colored negative image, although different mechanisms are involved for each image.

The silver developing radical, here hydroquinone, is oxidized to quinone in the areas of development. The quaternary ammonium radical is present in an alkaline environment of sufficient concentration such that the enamine derivative is generated. This active methylene group attacks only the quinone and not the hydroquinone to form a higher molecular weight product by a mechanism known as an oxidative coupling, which product contains an active methylene group that can in turn continue to attack a quinone radical such that an imagewise distribution of a still higher molecular weight non-diffusible product is formed as a function of development. Since in the preferred embodiment, the quinone and the enamine are part of the same molecule, it is seen that a polymeric product containing a continuously repeating unit is formed. Since this repeating unit is itself a chromophoric group, the negative image will be colored. It is likewise seen that by varying the nature of the quaternary ammonium radical, a different chromophoric group will be created, giving rise to variously colored images in the negative as is desired.

It is likewise seen that by appropriate choice of enamine generators a mixture of chromophoric groups can be created such as to give rise to black images.

Positive image formation is obtained by transferring by imbibition at least a portion of the imagewise distribution of unoxidized developing agent and enamine generator, to a superposed image-receiving layer. Since in the preferred embodiment both of these moieties form parts of the same molecule, it is seen that the problem of insuring that both moieties transfer to said image-receiver is alleviated. At the site of positive image formation, the transferred developing agent containing enamine groups reacts with the cycloammonium quaternary salt found in the image-receiving element to form a cyanine dye image in the areas of said element corresponding to the unexposed and undeveloped areas of the photosensitive element.

The color of the positive image may be the same or different from the color of the negative image as is desired. Control of color is obtained by the choice of the moieties which react with the enamine derivative. In the negative, the color is dependent upon the structure of the silver halide developing radical and in the positive upon the structure of the cycloammonium quaternary salt. It is also to be seen that the converse selection process can also be exercised. That is, given a specific structure for the developing radical, and a given cycloammonium quaternary salt, the enamine generator can be chosen to give desired chromophores in both the positive and negative. Thus, it is possible to obtain either a warm colored negative image and a cool colored positive image or vice versa, or both images of substantially the same color. It is likewise apparent that by the choice of particular enamine generators, that yellow, cyan and magenta chromophoric groups can be created in the positive and as such will find utility in a multicolor photographic process.

Control of pH is very important to the operation of the mechanisms involved for obtaining both the positive and negative images. A highly alkaline environment is necessary for the generation of the enamine derivative of the quaternary ammonium radical and also for the oxidative coupling reaction to form the colored polymeric negative image. On the other hand, the coupling-displacement reaction involved in the transfer image formation must take place at a pH which does not give rise to oxidized developing agent (e.g., by aerial oxidation) if the coupling-displacement reaction is to occur in preference to a repetition of the oxidative coupling reaction. By lowering the pH in the positive element, this nondesired reaction is prevented. Methods for achieving this pH reduction have been previously discussed.

It is to be seen that the image-forming system of the present invention gives rise to a negative image from which high quality information readout can be obtained. This is due to the fact that the image is derived from two sources, namely, the imagewise distribution of developed silver, and polymeric dye of the oxidative coupling. Since the epsilon of the dye formed and the covering power of the developed silver are cumulative, it is seen that for a given amount of exposure, a negative image of greater than normal density will be obtained.

The invention will be illustrated in greater detail in conjunction with the following specific examples which set forth representative preparations of the novel silver halide developing compounds of this invention, which preparations are not, however, to be limited to the details therein set forth and are intended to be illustrative only.

EXAMPLE I Preparation of N- y-(2,5'-dihydroxyphenyl) propyl-4-methylquinolinium bromide The 3-(2',5-dimethoxyphenyl)propanal, 34.0 g., 0.2 mole, was dissolved in 400 ml. of 95% ethanol. Sodium borohydride, 7.4 g., 0.2 mole, was added and the reaction mixture refluxed two hours. The solvent was removed in vacuo and water and ethyl ether were added. The ether extract was washed with water, dried (anhydrous magnesium sulfate) and concentrated to a heavy oil. The oil, 27 g., 79%, 3-(2',5'-dimethoxyphenyl)propanol was used directly. An infrared analysis showed that no aldehyde remained unreacted.

The 3-(2',5'-dimethoxypheny1)propanol, 27 g., 0.137 mole, was cooled to and phosphorous tribromide g., 0.074 mole, was added dropwise with stirring. The reaction was allowed to rise to room temperature and was stirred for an additional two hours and finally heated at 80 for /2 hour. The reaction mixture was poured into ice water and the product extracted into ethyl ether. The ether was washed with water and dried. The crude 3-(2',5-dimethoxyphenyl)propyl bromide was obtained by removal of the ether.

Attempts to purify a sample of the crude product by distillation at 18 mm. pressure and a temperature of 155 C. gave a clear liquid which was largely converted to a methoxy chroman. Because of this sensitivity to heat, the crude product was used directly in the synthesis of the quaternary salt.

The propyl bromide product, 5.6 g., 0.04 mole, and 4- methylquinoline, 5.6 g., 0.04 mole, were disolved in This compound is a vinylog of the 2-methylquinoline compound, which is capable of generating an enamine.

EXAMPLE II Utilizing a procedure similar to the one set forth in Example I, the compound of the following formula was prepared:

| [CHzk- Br- It was a yellowish solid molecular weight 324, that was soluble in water and slightly soluble in methyl cellosolve. The melting point was 220221 C.

EXAMPLE III Utilizing a procedure similar to the one set forth in Example '11, the compound N-y-(2',5'-dihydroxyphenyl) propyl-2-methylquinolinium bromide was prepared. It was a yellow solid, molecular weight 374, that was soluble in alkali and somewhat soluble in methyl cellosolve and ethanol. The melting point was 252-253 C.

The following nonlimiting examples set forth representative preparations of the cycloammonium compounds utilized in the obtainment of colored positive images, by the mechanism described herein.

EXAMPLE IV Preparation of 1-[3'-sulfopropyl]-2-(p-dodecyl)phenylthioquinolinium betaine 16.4 g. of 2-chlor0quinoline, molecular weight 163.6, 30.8 g. of 4-dodecyl thiophenol, molecular weight 278.5, 20.2 g. of triethyl amine and cc. of ethanol were placed in a flask fitted with a reflex condenser and refluxed for 4 hours. After removal of the solvent, 600 cc. ether was added and the triethyl amine hydrochloride which separated was removed by filtration. The filtrate was washed with sodium hydroxide, ammonium chloride and water. The ether layer was dried and the ether was removed by vacuum evaporation. 40.3 g. of 2-(p-dodecyl) phenyl-thioquinoline was prepared. Of this, 11 g. were mixed with 4.2 g. of 1,3-propane sultone, molecular weight 122.1, and heated in an oil bath at a temperature of about 145 for 6 hours after which time it was poured into acetone. A solid separated which was collected by suction filtration, washed with acetone and then with ether. This solid was recrystallized from isopropyl alcohol to give whitish micro crystals.

The spectral analysis of this product indicate absorption peaks at 241 millimicrons, e=12,720; 245 millimicrons, -e=13,600; 260 millimicrons, e=3,700; and 310 millimicrons, e=3,680 in 95% ethyl alcohol.

EXAMPLE V Utilizing techniques similar to those set forth in the previous example, the compound 1-ethyl-2-phenyl-thioquinolinium mesylate was prepared from the reaction of 2-phenyl-thioquinolinium with ethyl methane sulfonate.

It is readily seen that other compounds of a similar nature can be prepared utilizing similar techniques and other nitrogen-containing compounds and thio-containing compounds.

The invention will be illustrated in greater detail in conjunction with the following specific examples which set forth representative processes and which are not intended to be limiting, but are meant to be illustrative only, of the image-forming mechanisms comprising this invention.

EXAMPLE VI A photosensitive element was prepared by coating a gelatin subcoated film base at a speed of 10 feet per minute with a solution comprising 1 g. of N-v-(2,5'- dihydroxyphenyl)propyl 2 methylquinolinium bromide which was dissolved in a solution comprising 5 g. of cellulose acetate hydrogen phthalate dissolved in 100 cc. of a 1:1 mixture, by volume, of ethanol and methyl Cellosolve. A 2% gelatin layer was overcoated thereupon at a speed of 10 feet per minute. After this coating dried, a blue-sensitive silver iodobromide emulsion was coated thereupon at a speed of 5 feet per minute and allowed to dry. This photosensitive element was exposed and processed by spreading, between the thus exposed photosensitive element and a superposed image-receiving element, an aqueouse processing composition comprising:

Water1 cc.

Hydroxyethyl cellulose-3.9 g. p-rnethylaminophenyl-- g.

The image-receiving element comprised cellulose acetate coated with a layer of a partial butyl ester of poly(ethy1- ene/maleic anhydride) followed by a coating solution of 1 g. of gelatin and 2 g. of l-ethyl-2-pheny1 thioquinolinium mesylate in 20 cc. of ethanol and 80 cc. of water. This layer was overcoated with a solution of 3 g. of cellulose acetate hydrogen phthalate dissolved in 100 cc. of tetrahydrofuran. After an imbibition period of approximately one minute, the image-receiving element was separated and contained a pink positive image. The color of the negative image was dark blue.

EXAMPLE VII A photosensitive element was prepared by coating 9. gelatin subcoated film base at a speed of 15 feet per minute with a solution comprising about 2 g. of N-'y-(2',5'- dihydroxyphenyl)propyl 2 methylquinolinium bromide which was dissolved in a solution of 5 g. cellulose acetate hydrogen phthalate in 0 cc. of a 1:1 mixture, by volume, of methoxy ethanol and ethanol. After this coating dried, a blue-sensitive silver iodobromide emulsion was coated thereupon at a speed of 5 feet per'minute and allowed to dry. This photosensitive element was exposed and processed by spreading, between the thus exposed photosensitive element and a superposed image-receiving element, an aqueous processing composition comprising:

Waterl00 cc.

KOH1 1.2 g.

Hydroxyethyl cellulose-3.9 g. Benzotriazole--l.0 g.

The image-receiving element comprised cellulose acetate coated with a layer of a partial butyl ester of poly(ethylene/maleic anhydride), followed by a coating solution of 10 g. of polyvinyl pyrrolidone and 2 g. of 1-[3-sulfopropyl]-2-(p-dodecyl)phenyl-thioquinolinium betaine in 50 cc. of methanol and 507 cc. ethanol. This layer was overcoated with a coating solution of 2 g. cellulose acetate hydrogen phthalate dissolved in ml. of tetrahydrofuran and 10 ml. ethyl acetate. After an imbibition period of approximately one minute, the image-receiving element was separated and contained a magenta positive image. The color of the negative image was dark blue.

Processing can be effected in the presence of an auxiliary or accelerating silver halide developing agent which is substantially colorless, at least in the unoxidized form. Particularly useful are substituted hydroquinones, such as phenylhydroquinone, 4'-methylphenylhydroquinone, toluhydroquinone, tertiary-butylhydroquinone, and 2,5-triptycene diol. These hydroquinones may be employed as components of the processing composition or they may be incorporated in one or more layers of the negative. A small amount only of such auxiliary developing agents should be used in order not to terminate the polymer chain too early. The color provided by the participation of such compound in the oxidative coupling reaction is the same as that provided by the principal developing agent, since the resulting chromophoric group is the same. Another reason for using only a small amount of such compound is that an excess amount thereof might tend to inhibit the diffusion of enamine moieties to the image-receiving layer.

Modifications of the film structure, in addition to those already discussed, are included within the scope of the invention.

It is possible to make two or more transfer prints from the photosensitive element by employing a quantity of enamine radicals and silver halide developing radicals in excess of that needed to provide a single transfer print. By appropriate control of diffussion rates and imbibititon time, a quantity of image-forming reagents at least sufficient for a second transfer print remains in the processed photosensitive element. The second transfer print may be obtained by pressing the photosensitive element against a new print-receiving element in the presence of a processing solution effective to transfer a second imagewise distribution of enamine radicals.

In all products employed in the practice of the invention, it is preferable to expose the negative material or photosensitive element from the emulsion side. It is therefore desirable to hold the photosensitive element and positive sheet material together at one end thereof by fastening means, not shown, but comprising hinges, staples, or the like, in such manner that the photosensitive element and the positive element may be spread apart from their positions illustrated in FIG. 1. When the film unit is of the roll film type, the photosensitive element and the positive sheet are wound into separate rolls and the free ends of said rolls are connected together, in the manner described.

This invention is especially useful in composite film units intended for use in a Polaroid Land Camera, made by Polaroid Corporation, Cambridge 39, Mass., or a similar camera structure such, for example, as the roll film type camera forming the subject matter of U.S. Pat. No. 2,435,717, issued to Edwin H. Land on Feb. 10, 1948, or the film pack type camera shown in U.S. Pat. No. 2,991,702, issued to Vaito K. Eloranta on July 11, 1961. In general, such composite film units comprise a photosensitive element, an image-receiving element and a rupturable pod containing an aqueous alkaline processing solution, and may take the form of roll film, sheet film or film packs. The elements and pod are so associated with each other that, upon processing, the photosensitive element may be superposed on the imagereceiving element and the pod may be ruptured to spread the aqueous alkaline processing solution between the superposed elements.

Furthermore, the invention is useful for copying purposes from color separation positives with any of the types of film units described. Of course, when the invention is used in the production of photographic originals, the spectral sensitivity of the different emulsion layers must be suitably chosen. For instance, a panchromatic or a red-sensitized silver halide emulsion is preferably employed for producing a cyan positive image.

While the above discussion has referred to oxidative coupling taking place between an in situ generated enamine moiety and an oxidized silver halide developing radical, both of which have been shOWn to be present as parts of the same molecule, as per the formula:

DEVLINKEN as defined previously, it will be appreciated that the same oxidative coupling can take place between molecules of the two compounds of the formulae:

DEVLINKDEV and EN-LINKEN wherein the moieties DEV, LINK and EN are as defined in the formula:

DEV-LINK-EN This latter mechanism can best be utilized for forming colored negative images of high quality.

Similarly, it is seen that the cycloammonium quaternary compounds can be bifunctional and as such would include structures of the nature of:

such that the chromophore formed by the reaction with the enamine in the image-receiving element would be a polymeric dye.

Throughout the specification and appended claims the expression positive image has been used. This expression should not be interpreted in a restrictive sense since it is used primarily for purposes of illustration, in that it defines the image produced on the image-carrying layer as being reversed, in the positive-negative sense, with respect to the image in the photosensitive element. As an example of an alternative meaning for positive image, assume that the photosensitive element is exposed to actinic light through a negative transparency. In this case the latent image in the photosensitive element will be a positive and the image produced on the imagecarrying layer will be a negative. The expression positive image is intended to cover such an image produced on the image-carrying layer.

In the preceding portions of the specification, the expression color has been used. This expression is intended to include the use of a plurality of colors to obtain black, as well as the use of a single black dye.

Since certain changes may be made in the above products, compositions and processes without departing from the scope of the invention herein involved, it is intended that all matter contained in the above description shall be interpreted as illustrative and not in a limiting sense.

What is claimed is:

1. A process for forming images in color, which comprises:

(a) developing an exposed silver halide stratum with an aromatic silver halide developing agent which contains at least one hydroxyl group in the developing radical and which agent also contains a substituent capable of generating an enamine moiety, said developing radical being capable upon oxidation of interaction with an enamine by an oxidative coupling reaction, said silver halide developing agent being present at a pH such that said enamine moiety is generated;

(b) immobilizing said developing agent in developed areas of the silver halide stratum by reaction of oxidized developing radicals with enamine moieties, whereby a nondiifusible dye is formed in said developed areas;

(0) transferring at least part of the unoxidized developing agent from the undeveloped areas of the photosensitive layer, by imbibition, to an image-receiving element in superposed relationship with said silver halide stratum; and

(d) reacting the transferred enamine moieties with a cycloammonium quaternary compound of the formula:

I R S-f z wherein R is an alkyl or haloalkyl group of from 1 to 12 carbon atoms inclusive, R is a ballast group, and Z comprises the atoms necessary to complete a heterocyclic ring, and which compound is found in said image-receiving layer to impart to said imagereceiving layer a reverse dye image of the developed image. 2. The process of forming images in color as defined in claim 1 wherein the silver halide developing agent is a compound of the formula DEV-LINK-EN wherein DEV is an unsubstituted, alkylsubstituted or halogen substituted monovalent radical selected from the group consisting of phenyl and naphthyl rings, substituted in ortho or para positions with respect to each other by -OH and NH at least one of said positions being substituted by --O'I-I; or the precursors thereof, wherein the precursor group for OH is an alkoxy or alkoxymethoxy group, and the precursor for -NH is -NO;;;

LINK is a divalent linking radical of the formula:

e z- OC2H4] m 2] n' 2 or of the formula:

"" e Z 2 4]m 2]n 2 wherein A is selected from the group consisting of oxygen or sulfur, e is 1 or 0, m is a number of from 0 to 4 inclusive, n is a number of from 0 to 8 inclusive, the sum of m +n being not greater than 8; and

EN is a cyclic or acyclic quaternary ammonium radical which is capable of generatingan enamine and which radical is bonded through the pentavalent nitrogen atom thereof to LINK.

3. The process of claim 2 wherein DEV- is an ortho or para dihydroxyphenyl radical, --LINK-- is an alkylene radical of from 2 to 8 carbon atoms inclusive and --EN is a cyclic quaternary ammonium radical which is capable of generating an enamine and which radical is bonded through the pentavalent nitrogen atom thereof to LINK.

4. The process of forming images in color as defined in claim 1 wherein the cycloammonium quaternary compound is selected from the group consisting of l-[3-sulfopropyl]-2- (p-dodecyl)pheny1 thioquinolinium betaine and l-ethyl-Z-phenyl thioquinolinium tosylate, and 1-ethyl-2- phenyl thioquinolinium mesylate, and the silver halide developing agent is -N-'y-[2,5-dihydroxyphenyl]propyl-2- methylquinolinium bromide.

5. The process as defined in claim 1 including the step of lowering the pH on the image-receiving layer to a level less than is necessary for the oxidative coupling reaction prior to the separation of said layer from its superposed relationship with the silver halide stratum at some stage of said process after said imagewise distribution of dye has been formed on said image-receiving layer.

6. The process of forming images in color as defined in claim 1 wherein the image-receiving layer and the silver halide stratum are separated from superposed relationship at some stage of said process after the imagewise distribution of dye has been formed on said imagereceiving element.

7. A process of forming images in color as defined in claim 1 wherein the image of the photosensitive element is of a color different from the color of the dye image formed on the image-receiving element.

8. A diifusion transfer process comprising the steps of developing an exposed photosensitive silver halide stratum with an aromatic silver halide developing agent which contains at least one hydroxyl group in the developing radical and which agent contains a substituent capable of generating an enamine moiety, generating enamine moieties, oxidizing said developing agent as a function of development to provide in developed areas of said silver halide stratum an imagewise distribution of a substantially nondiifusible polymeric dye by an oxidative coupling reaction, transferring at least a portion of the imagewise distribution of unoxidized developing agent from the undeveloped areas of said silver halide stratum to a dyeable superposed image-receiving layer, and forming a reverse dye image thereupon by the reaction of enamine moieties with a cycloammonium quaternary compound found in said image-receiving layer.

9. The process as defined in claim 8 including the step of lowering the pH on the image-receiving layer to a level less than is necessary for the oxidative coupling reaction prior to the separation of said layer from its superposed relationship with the silver halide stratum at some stage of said process after said imagewise distribution of dye has been formed on said image-receiving layer.

10. The process as defined in claim 8 wherein the developing agent is a compound of the formula:

DEV-LINK- EN wherein DEV is an unsubstituted, alkylsubstituted or halogen substituted monovalent radical selected from the group consisting of phenyl and naphthyl rings, substituted in ortho or para positions with respect to each other by OH and -NH at least one of said positions being substituted by OH; or the precursors thereof, wherein the precursor group for OH is an alkoxy or alkoxymethoxy group, and the precursor for NH is NO LINK is a divalent linking radical of the formula:

e 2" 2 4]m 2]n 2' or of the formula:

e 2 2 4] m" CH2]11""CH2 wherein A is selected from the group consisting of oxygen or sulfur, e is 1 or 0, m is a number of from O to 4 inclusive, n is a number of from 0 to 8 inclusive, the sum of m-l-n being not greater than 8; and

EN is a cyclic or acyclic quaternary ammonium radical which is capable of generating an enamine and which radical is bonded through the pentavalent nitrogen atom thereof to LINK.

11. The process as defined in claim 8 wherein the developing agent is N-y-[2,5'-dihydroxyphenyl]propyl-2- methylquinolinium bromide, and the cycloammonium compound is selected from the group consisting of l-ethyl- 2-phenyl thioquinolinium mesylate, l-ethyl-Z-phenyl thioquinolinium tosylate and 1 [3' sulfopropylJ-Z-(p-dodecyl) -thioquinolinium betaine.

12. A photographic product comprising a photosensitive stratum having a liquid-permeable portion including a layer of a dye free photosensitive silver halide emulsion comprising silver halide dispersed in a polymeric matrix, an image-receiving layer including a dyeable material for receiving a transfer image, and which element contains a cycloammonium quaternary compound, a container holding a liquid, said photosensitive stratum, said imagereceiving layer and said container being attached together to permit at least a portion of said image-receiving layer and said photosensitive stratum to be superposed with said container so positioned as to be capable of being ruptured and of releasing its liquid content to at least partially permeate said superposed image-receiving layer and said photosensitive stratum, including said emulsion, said product having positioned therein photographic processing materials, said materials including an aromatic silver halide developing agent containing at least one hydroxyl group in the developing radical and which agent contains a substitutent capable of generating an enamine moiety soluble in said liquid and wherein said developing radicals are capable upon oxidation thereof, of interaction with said enamine moieties to provide an imagewise distribution of a polymeric dye in said photosensitive stratums developed areas, said materials being rendered effective upon the rupture of said container for providing in said emulsion a substantially uniform distribution of said enamine moieties and said developing radicals whereby to develop a latent image in said emulsion, form an imagewise distribution of a polymeric dye and provide in said emulsion enamine moieties in mobile condition and transportable from said photosensitive stratum to said image-receiving layer for imparting to the dyeable material a positive dye image by the interaction of said enamine moieties with a cycloammoniumquaternary compound found in said image-receiving layer.

13. A photographic product as defined in claim 12 wherein the developing agent is of the formula:

DEV-LINK-EN wherein DEV is an unsubstituted, alkylsubstituted or halogen substituted monovalent radical selected fromthe group consisting of phenyl and naphthyl rings, substituted in ortho or part positions with respect to each other by OH and NH at least one of said positions being substituted by --OH; or the precursors thereof, wherein the precursor group for OIE is an alkoxy or alkoxymeth oxy group, and the precursor for -NH is -NO LINK is a divalent linking radical of the formula:

- A -CH [OC 4]m[ 2ln z or of theformular wherein EN is a cyclic or acyclic quaternary ammonium radical which is capable of generating an enamine and which radical is bonded through the pentavalent nitrogen atom thereof to LINK.

14. A photographic product as defined in claim 12 wherein the cycloammonium quaternary compound is selected from the group consisting of 1-[3'-sulfopropyl]-2- (p-dodecyl)phenyl thioquinolinium betaine, 1-ethyl-2- 28 phenyl thioquinolinium tosylate and l-ethyl-Z-phenyl thioquinolinium mesylate and the developing agent is N-'y- [2',5-dihydroxyphenyl]propyl-Z-methylquinolinium bromide.

References Cited UNITED STATES PATENTS 3,309,199 3/1967 Ross 9629 NORMAN G. TORCHIN, Primary Examiner A. T. SURO PICO, Assistant Examiner US. Cl. X.R. 96S5 

